1. Field of the Invention
The present invention is related in general to polymerization processes and polymers made thereby. The invention is related in particular to processes for the production of polyols and polyurethanes made therefrom.
2. Description of the Prior Art
Polyols, both polyether and polyester glycols are one of three main components which constitute most types of polyurethane elastomers. The polyols also find use in other related plastics, applications, and processes such as reaction injection molding (RIM). Another major component of polyurethane is polyisocyanate material such as toluene diisocyanate (TDI), methylene-bis-diisocyanate (MDI), and other variations thereof. The third major component of polyurethanes is the chain extender which forms larger molecules that provide properties characteristic of polyurethanes. These chain extenders include diethyl toluene diamine (DETDA), 4,4'-methylenebis-o-chloroaniline (MOCA), butanediol, and other aromatic diamines.
The polyol component of polyurethanes normally constitutes about 40-80% of the finished polymer. Polyols used in the past include those of the linear type such as polytetramethylene ether glycol (PTMEG) and those of the branched type such as polypropylene ether glycol (PPG). The linear polyols are normally used in the production of cast elastomers and thermoplastics such as solid tires and wheels, printing reels, conveyor belts, hydraulic hoses, cable jacketing, industrial fiber coating, magnetic tape binders, imitation leather goods, adhesives, elastic fibers, and many other uses.
Polyurethanes made from PTMEG have been shown to be thermally and oxidatively stable with better physical properties than those polyurethanes based, for example, on polypropylene ether glycol (PPG). However, PTMEG is about twice as expensive as the readily available PPG.
The polyester polyols are used in non-foam urethanes and have been shown to have high tensile strength, better high temperature properties, and other more favorable characteristics than the polyether polyurethanes. However, polyurethanes made from polyester polyols tend to have a lower hydrolytic stability than polyurethanes made from polyethers.
There exists a need to produce other hydroxy-terminated polymers for the production of polyurethanes so as to provide products with desirable physical properties including good hydrolytic stability. Especially needed are polyols in the 1,000-2,000 molecular weight range.